广西栗木钨锡铌钽矿区流体包裹体及氢氧同位素研究

Study on Fluid Inclusions and H-O Isotope of the Limu Tungsten-Tin-Niobium-Tantalum Orefield in Guangxi

本文通过对广西栗木矿区金竹源矿床和水溪庙矿床的流体包裹体研究,得出该矿区流体包裹体主要有两相H_2O-NaCl和H_2O-NaCl-CO_2两种类型。显微测温结果表明:两相H_2O-NaCl型流体包裹体均一温度主要集中于181.9~258.8℃,盐度w(Na Cleq)主要集中于4.01%~6.87%,密度0.690~0.988 g/cm3;H_2O-NaCl-CO_2型流体包裹体均一温度为178.5~331.1℃,主要集中在两个温度段,分别为高-中温段(265.3~315.5℃)和中-低温段(202.3~264.1℃),盐度w(NaCleq)主要集中在0.21%~5.05%,密度为0.678~0.886 g/cm3。栗木矿区成矿流体有两个温度集中段,且具有低盐度、低密度的特征。氢氧同位素研究结果表明:金竹源矿床钨锡铌钽矿化花岗岩石英δD值为-73.6‰^-62.8‰,δ^(18)OV-SMOW值为7.5‰~8.9‰,计算得δ^(18)OH2O值为6.00‰~7.40‰;水溪庙矿床钨锡铌钽矿化花岗岩石英δD值为-73.8‰^-58.3‰,δ^(18)OV-SMOW值为11.0‰~13.2‰,计算得δ^(18)OH2O值为9.50‰~11.70‰,水溪庙矿床含钨锡石英脉石英δD值为-75.3‰^-56.6‰,δ^(18)OV-SMOW值为11.8‰~14.1‰,计算得δ^(18)OH2O值为2.20‰~4.50‰。栗木矿区钨锡铌钽矿化花岗岩成矿流体来源于岩浆水,含钨锡石英脉成矿流体来源于岩浆水和大气降水的混合流体。

This study focused on fluid inclusions trapped in quartz from the Jinzhuyuan and Shuiximiao deposits in the Limu orefield of Guangxi. These inclusions can be divided into H2O - NaCl type and H20 - NaC1 - CO2 type. Microthermometric results show that the H2O - NaCl type primary flu- id inclusions have a hmnogeneous temperature range of 181.9 ~258.8℃and salinity of 4.01% ~ 6.87% NaCleq with density in the range of 0. 690 0. 988 g/cm3. In contrast, the H20 - NaC1 - COztype fluid inclusions have a homogeneous temperature range of 178.5 ~ 331. 1℃ , which are mainly concentrated in two stages： the hyperthermal- rnesothermal stage with temperature range of 265.3 -315.5℃ and the mesothermal -hypothermal stage with temperature range of 202.3 ~ 264. 1 ℃. Their salinity concentrates in 0. 21% ~ 5.05% NaCleq with density 0. 678 ~ 0. 886g/cm3. In summary, the ore - forming fluids of the Limu orefield can be divided into two stages, both having low salinity and low density. The hydrogen and oxygen isotope indi- cates that δD, δ18 Ov-SMOW and δ18 OH2 o of quartz in the W -Sn -Nb -Ta mineralized granite of the Jinzhuyuan deposit are -73.6‰ - -62.8‰, 7.5‰ - 8.9‰ and 6.00‰ - 7.40 ‰, respectively. Those of quartz in the W - Sn - Nb - Ta mineralized granite of the Shuiximiao deposit are - 73.8‰ - - 58.3‰, 11.0‰ ~ 13.2‰ and 9.50‰ - 11.70 ‰, respectively. Those of quartz in the W - Sn mineralized quartz vein of Shuiximiao deposit are - 75.3‰ ~ - 56.6‰, 11.8‰ N 14.1‰ and 2. 20‰ ~ 4.50‰, respectively. In the Limu orefield, the source of ore - forming fluids of W - Sn - Nb - Ta mineralized granite is magmatic water, while the ore - forming fluids of W - Sn mineralized quartz veins originate from the mixture of magmatie water and atmospheric water.